In recent years, a technique of attaching an input device referred to as a touch panel or a touch sensor to a display surface of a display device and sensing and outputting an input position when input operations are performed by contacting the touch panel with a finger or an input tool such as a stylus pen has been known.
One sensing method for sensing contact positions at which a finger or the like has contacted the touch panel as an input device is the electrostatic capacitive method. In an electrostatic capacitive type touch panel, a plurality of capacitive elements each made up of a sensing electrode are provided in a plane of the touch panel. Then, the input positions are sensed by utilizing the characteristics that the electrostatic capacitance of capacitive elements changes when performing input operations by contacting the capacitive elements with a finger or an input tool such as a stylus pen.
For example, Japanese Patent Application Laid-Open Publication No. 2013-45466 (Patent Document 1) discloses a technique of a touch sensor device including: a touch screen having Tx lines, Rx lines crossing the Tx lines and touch sensors formed between the Tx lines and the Rx lines; and a touch screen drive circuit which senses a position of a touch input.